Reuse is one thing, but no code should be unmaintainable. If code is written in an unmaintainable style it is also hard and error-prone to develop in the first

Reuse is one thing, but no code should be unmaintainable. If code is written in an unmaintainable style it is also hard and error-prone to develop in the first place. But I agree about YAGNI, and SOLID principles are not always appropriate.